Recently, there is seen frequently the tibial fracture due to the increased traffic accident and the high industry. Rigid intramedullary nailing is the method of choice in tibial shaft fracture, early weight bearing and joint motion. Between Jan.1993 and Dec. 1994, we treated 93 tibial shaft fractures with reamed intramedullary nails(55 cases) & unlearned intramedullary nails(38 cases). We analyzed the effects of these two methods, and the following results were obtained. 1. Of 93 fractures, 32 fractures were open and 61 fractures were closed. 2. The most common cause was traffic addicent. Among the 93 cases, 60 cases were male and 33 cases were female, the most common age were ranged from 30-39 year, involving 36 cases. 3. The mean durations of the bone union were 19.7 weeks in closed fracture with treated by reamed nail and 22.1 weeks in closed fracture with unlearned. The mean duration of the bone union were 24.5 weeks in open fracture with reamed and 22.4 weeks in open fracture with unlearned. The complications of intramedullary nail are angular deformity, infection, delayed and nonunion, and screw breakage.